Sources of Heat

As you have learned, food has energy stored
in it which can be released as heat. Many other substances contain similar
energy sources. Fuels are a good example. Solid fuels, such as coal, liquid
fuels, such as gasoline and oil, and gaseous fuels, such as propane and
natural gas, such as propane and natural gas, all contain chemical energy.
This chemical energy can be released as heat through the chemical process
of burning. Just as an automobile engine burns fuel, your body burns food
in the process of digestion. (Digestive burning releases the heat gradually,
so there is no damage to your body.) What foods have you eaten today to
supply the energy your body needs? What would happen if you missed some
meals?

Friction

If the particles in a substance move more quickly, the average
energy increases, and the temperature of the substance goes up. You can
use the push or pull of a mechanical force to make the particles of a substance
move more quickly. Rub your hands together for 30 s, then place your palms
on your cheeks. The heat you feel is the result of a mechanical force called
friction. Often, lubricants, such as oil, are used to decrease friction
and the amount of heat created in machines.

Nuclear Reactions

If you have
been outside on a summer day, you have felt the heat from the Sun. The
Sun produces this heat through a nuclear reaction. Inside the Sun, atoms
of hydrogen are joined together to form a large atom, helium. In this process,
called fusion, a small amount of the mass of the hydrogen atoms is transformed
into energy. The energy release uses Albert Einstein's famous formula,
E=mc². (in the formula, E stands for energy in joules, m stands for
mass in kilograms, and c stands for the speed of light in metres per second.)
Technologists can also create nuclear reactions through a process called
fission. In a fission nuclear reaction, atoms of a material like uranium
are split into smaller atoms. This splitting also causes a small amount
of mass to be transforms into energy. Controlled nuclear fission can be
carried out in a nuclear reactor, such as the Canadian-designed CANDU reactor.

Electricity

As
electricity moves through a wire, it causes the particles in the wire to
move. If the particles in a substance move more quickly, the average energy
increases, and the substance gets hotter. Some metals release more heat
than others when electricity passes through them. For example, iron releases
more heat then copper. In order for electricity to be used as a source
of heat, we must first produce the electricity. There is more than one
way to produce electricity. In Canada, we are lucky to have many large
river systems. The energy is moving water can be used to produce hydroelectricity.
Much of our electricity is also produced at generating stations that burn
fuels such as coal, oil, or natural gas, or at nuclear generating stations.
Do you know where electricity you use comes from or how it is created?

Self Check

List the ways that heat can be produced. Give an example of how each is
used in your daily life.

In each of the following situations, state the type of energy that is a
source of heat.

a) An iron is used to press clothes.
b) A match burst into flames.
c) A greenhouse produces tropical plants.
d) A toaster is used in preparing breakfast.
e) A nail becomes warm as it is pounded into a board.
f) The engine of a gasoline mower overheated after operating
without oil.

Journal Entry

Imagine a technological breakthrough in which a totally new
and cheap source of heat is discovered. How would it affect you? How would
it affect business and industry?